LocalMicTrack

LocalMicTrack is created by RTCEngine.getLocalMicTrack(...). Microphone capture is decoupled from joining a channel and publishing audio: the app must explicitly call startCapture(...) to open the shared microphone, then publish through RTCEngine or RTCChannel.publishLocalAudio(...). The same LocalMicTrack can be published to multiple channels. Unpublishing from one channel doesn’t stop capture; stopCapture() closes the shared data source and affects every channel still using the track.

startCapture(listener)

fun startCapture(listener: RTCResultListener?)

Opens microphone capture. Repeated calls with the same parameters are idempotent. After it succeeds, you can read the volume, receive local PCM callbacks, or publish to a channel.

Parameter	Type	Description
`listener`	`RTCResultListener?`	The start result; can be `null`. For failure codes, see Error codes.

stopCapture()

fun stopCapture()

Closes shared microphone capture. Calling it when capture hasn’t started is idempotent.

getVolume()

fun getVolume(): Int

Returns the real-time microphone volume in dBFS, roughly in the range [-60, 0]; returns the implementation’s silence value when not capturing.

switchMicDevice(deviceId)

fun switchMicDevice(deviceId: String)

Switches the microphone input device. deviceId comes from getMicDevices() and is valid only while the device stays connected; switching during capture rebuilds the recording pipeline.

getMicDevices()

fun getMicDevices(): List<MicDeviceCapability>

Returns the capabilities of the microphone input devices currently available on the system. For fields, see Types. getMicDevices() and switchMicDevice(...) on the Engine are convenience entry points to the same shared capture module.

Local PCM callback

rtcEngine.setRtcLocalAudioFrameEvent(object : RTCLocalAudioFrameEvent {
    override fun onLocalAudioFrame(
        pcm: ByteArray?,
        sampleRate: Int,
        channelCount: Int,
        audioFormat: Int
    ) {
        // Don't perform time-consuming I/O on the callback thread
    }
})

val micTrack = rtcEngine.getLocalMicTrack(PreOptionMic.def)
micTrack.startCapture(listener)

Registering the frame listener alone doesn’t open the microphone. For full parameters, see RTCLocalAudioFrameEvent.

Overview

Web SDK

Android SDK

Swift SDK (iOS/macOS)

C SDK (server/embedded)

Python SDK (server-side AI)

Server API

startCapture(listener)

stopCapture()

getVolume()

switchMicDevice(deviceId)

getMicDevices()

Local PCM callback

​startCapture(listener)

​stopCapture()

​getVolume()

​switchMicDevice(deviceId)

​getMicDevices()

​Local PCM callback

startCapture(listener)

stopCapture()

getVolume()

switchMicDevice(deviceId)

getMicDevices()

Local PCM callback